How to Choose the Ideal Heat-transfer Fluid for Solar Water Heater ?

Solar water heaters are a great device. They save lots of money and are environment-friendly. Not to mention they are also a great apparatus to save the much-needed electricity. We all know the condition and rates of power in our country. Hence its always wise to go for a solar water heater.
solar water heater
In order to understand the ideal heat transfer fluid for a solar water heater, we first must understand the issues that crop up with it.

There are two major issues which affect the performance of a solar water heater:

  • Scaling
  • Corrosion


This happens when we use domestic water as a heat transfer fluid. Domestic water is laden with minerals i.e. hard water can damage the system due to scaling. This happens especially in hydronic solar water heating systems.Hard water usage results in calcium deposits in the collector, distributing piping and heat exchanger.This reduces the overall efficiency of the system.

solar water heater

Scale Formation

In case of solar water heaters that use other heat transfer fluids like glycol and antifreeze scaling can occur on the surface of the heat exchanger where the transfer of heat occurs to the domestic water. In some cases, scaling may cause valve and pump failures on the potable water loop.

Also Read: How To Build an Induction Heater and How Does it Work?


If your solar water heater is well designed and installed then there is minimal corrosion. In solar water heaters, most of the corrosion is galvanic in nature. You may ask that’s metals at play and what has the choice of fluid to do with it. In this case, the heat exchange fluid at times acts as the bridge for the ionic transfer.

Now, in a nutshell, we know what can go wrong with a specific choice of fluid used for heat exchange in the solar water heater. This gives us a very clear-cut indicator of how to choose the ideal heat exchange fluid for the solar water heater.

Following things should be to choose the best fluid :

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